Jet Diffusers are the back section of the jet that holds the jet into the hot tub or spa, they are very easy to replace and can save you allot of money if your looking into replacing the jets in your spa.
We have written a guide on how to replace hot tub jet diffusers in the article section - - Diffusers
Water Jet Diffusers made by WaterWay Products - replacement hot tub and spa water jet parts.